Imaging Modalities

Question 1

What is the role of CT in RT?

Answer 1

• gain insight of position and size of tumour and surrounding tissue

Question 2

What are the advantages of CT in RT?

Answer 2

• allows user to plan and calculate dose

- accurate dose distribution in planning od PTV and OAR

Question 3

What are the disadvantages of CT in RT?

Answer 3

• suboptimal tissue contrast
• doesn’t provide functional information
• bore size limitation for larger patient and immbolisation equipment

Question 4

What is the role of ultrasound in RT?

Answer 4

• form of IGRT which provides realtime trackinf (e.g. bladder filling)

Question 5

What are the advantages of ultrasound in RT?

Answer 5

• non-ionising
• real time
• markerless
• excellent soft tissue contrast

Question 6

What are the disadvantages of ultrasound in RT?

Answer 6

• image quality is user dependent
• exensive equipment and RT training required
• could decrease departmental efficiency

Question 7

What is the role of PET in RT?

Answer 7

• image fusion to identify extensive disease

- SPECT-CT imaes used in RT planning to precisly delineate the tumour volume

Question 8

What are the advantages of PET in RT?

Answer 8

• high accurate image fusion
• good indication of metastasis
• indication of LNs involvement

Question 9

What are the disadvantages of PET in RT?

Answer 9

• long waiting time
• not widely available in RT department
• expensive
• patient required to fast

Question 10

What is the role of MRI in RT?

Answer 10

• high quality soft tissue contrast

- increased accuracey of target delineation and contouring

Question 11

What are the advantages of MRI in RT?

Answer 11

• non-ionising

- captures organ motion

Question 12

What are the disadvantages of MRI in RT?

Answer 12

• not suitable for all patients (e.g. pacemaker)
• not compatable with TOS
• high cost and time
• magnetic field safety